Improvement in treadle-motions



UNITED STATES PATENT OFFICE.

ABRAHAM \V. HARRIS, OF PROVIDENGE, RHODE ISLAND.

IMPROVEMENT IN TREADLE-MOTIONS.

To all whom it may concern:

Be it known that I, ABRAHAM W. HARRIS, of Providence. in the county of Providence, in the State of Rhode Island, have invented a new and improved mode-of starting the crankshaft of sewing-machine tables and preventing the samefrom being turned in the wrong direction; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

The object which I accomplish with my invention is moving the crank of the drivingshat't of sewing-machine tables ofi' the centers, and by the same device prevent the shaft from being turned in the wrong or opposite direction from which it is designed to rotate.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

To illustrate myimproven'ient more clearly` I will use the present form ot' the Wheeler 85 Wilson sewing-machine table. This table has a crankshaft supported by the frame of the table. The crank ofthe shaft is connected by a. pitinan to a treadle which is operated by the foot and` imparts the required motion to drive the machine, and when starting the shaft is as liable to be turned in the wrong direction as in the right; also, the crank is liable to stop on its center. To obviate these didiculties, I apply a vibrating arm on the straight part ofthe crank-shaft, having a pawl within it that produces a binding action on the shaft. I connect this vibrating arm to an independent treadle, fr, by a pitnian. This treadle is located on the same axis-rod as the cranktreadle.. On the under side ot' this treadle, forward ofthe axis, is a stop, y, Figure l, resting on the licor, the object of which is to hold the toc of the treadle in the position as shown and to preventthe vibrating arm from dropping down out of position. When the crank is on its center, by a gentle pressure of the foot upon the heel of the independent treadle a binding action of the pawl is produced on the .shaft and moves the crank ott' the center. 'Ihus the shaft is put in motion and in the right direction. The motion is then kept up by the crank-treadle, as in the ordinary manner. The pawl assumes its former position by slightly raising the foot from the heel and bearing upon the toe of the independent treadle andthe assistance of a spring under the heel of the treadle. It then remains at rest, ready to be thrown into action when required.

We will now suppose the crank to bein any posit-ion than on its center. If the power applied to the crank-treadle be not requisite to turn the shaft in the right direction, a binding action is produced upon the shaft by the pawl -and the shaft will Ilot turn. The operator is then necessarily compelled to apply the power in the opposite direction from which it was first applied. The shaft then being relieved of the binding action of the pawl, the crank moves in the right direction and the motion is kept up, as in the ordinary manner.

I will now proceed to describe how thehinding action of the pawl is produced.

The vibrating arm a, Fig. 1is litted to the hub b, Fig. 3, which is secured to the crankshaft. Through the vibrating arm a, Fig. 3. a circular slot is cut, the outer circle of which forms an inclined plane and the inner circlel is formed by the outside of thehub b. In this slot, and in contact With the hubb,isacircular Wedge, c, the inner circle conforming to said hub and the outer circle forming the wedge, and the incline thus formed stands opposite to the incline of the vibrating arm a, and between the two inclines is a roll, d. This roll is held in contact with the twoinclined planes by means of a sprin g bearing against the end of the circular wedge. When the arm is moved upward, as indicated by the blue lines, Fig. 1, the roll binds between the two inclines and forces'theni apart, which creates a friction up on the hub b, and this being secured to the crank-shaft forces the shaft to rotate. The downward action of the arm ct liberates the binding action of the roll d and allows the vi-- brating arm to turn freely on the hub b. A

cap covers the slotin the vibrating arm, and Y is secured to the hub b.

I do not claim the roll cl of the above-described pa-Wl. Neither: do I con tine myself to any construction ofpawls, nor the employment ot' a single-acting pawl.

Having thus described my invention, what I desire to secure by Letters Patent is- A pawl or pawls acting by means of an in dependent treadle, in combination with the crank and crauktreadle of sewing-machine tables, as herein set forth.

' ABRAHAM IV. HARRIS.

Witnesses:

GEO. L. SAYLEs, WM. A. HARRIS. 

